The scaling of features in integrated circuits enables increased densities of electronic devices on the limited real estate of the integrated circuit chip. Generally, the performance of electronic devices on the integrated circuit chip (e.g., transistors, resistors, capacitors, etc) is a major factor considered during scaling of those devices. The factors affecting the electronic device performance can be, for example, a carrier mobility and saturation velocity. Group III-V element compounds, for example, gallium arsenide (GaAs), indium antimonide (InSb), indium phosphide (InP), and indium gallium arsenide (InGaAs) are known to have higher electron mobility and saturation velocity than silicon. These materials may thus provide superior device performance.
Typically, an isolation oxide or other isolation scheme is used to prevent parasitic leakage from a source to a drain of the transistor. Currently, on III-V transistors a semiconductor having a large band gap (Eg) is used as isolation. The parasitic leakage degrades the performance parameters of the III-V transistors. For example, the parasitic leakage path from the source to the drain causes increased off-state leakage current, degrades the sub-threshold slope of the current-voltage characteristics, and the ability of the device to completely turn off.